So, my friend and I are beginning to make plans for a PCT hike next summer and it occurred to me that since she got a DUI about 9 months ago she may not be able to enter Canada legally. Anyone happen to know how Canada's restriction against allowing anyone with a felony to enter the country might affect her in this situation?

In the states, DUI's are a misdemeanor unless there was some harm done to another person or she crashed or is a multiple offender. However, Canada views DUI's as a very serious crime and will deny entry unless a certain amount of time (between 5-10 years) has passed since her conviction (guilty or no contest, doesn't matter). If she want's to enter Canada before that time has passed she can apply for a Temporary Resident Permit at the border and pay a fee (around $200). When I talked to somebody at the Canadian Consulate they said most people are denied entry at the border when applying for a Temporary Resident Permit and it might be easier to apply through the Canadian Consulate. She would need to do this up to 6 months before her departure date and there is no guarantee that she'd get approved. If she has multiple offenses, DUI or anything else, there is a good chance she won't be approved. Basically she's screwed. Hope this helps some.

I only meant if she was crossing at a border check point or trying to get into Canada…I doubt she will have a problem if she's crossing some imaginary line while hiking. I don't know how far you have to go into Canada when hiking the PCT.

"For the first time, Pacific Crest Trail hikers are being warned that people who hike across the border from Canada into the United States are committing a federal crime, and risking a year in jail and a $5,000 fine.

In a June 1 letter to the Pacific Crest Trail Association, the U.S. Border Patrol urged the group to educate their members and other hikers to cross the border only at designated ports of entry." [posted in July of 2010]

This isn't likely to help folks with a DUI/DWI or anyone else looking to enter Canada from the PCT this year and maybe not next but perhaps the PCTA would like to approach Canada about expanding the remote border crossing permit system that is in place for the Superior/Quetico region:

As you may know the "Entry to Canada via the PCT" papers are filed with Canadian immigration. It takes a month or more to recieve an acceptance or a rejection.

The US is unlikely to be worried about hikers crossing into Canada at monument 78 so as long as you have the entry permit you can cross the border and hike the 8 miles to Manning Park BC, catch a bus to Vancouver and fly back to the states.
You would of course need to have a passport to return to the US that way.
I had some fellow hiker friends that were rejected by Canada.
(This advice could also work for southbound PCT'ers that wanted to avoid the lack of a US equivalent of an "entry via the PCT" form.)
Here is what they did:
Hike to monument 78 on the US/Canadian Border.
Turn around and hike 30 miles back to Harts Pass.
Hitch to Sedrow-Whooley.
Catch a bus to Seattle.

Southbound hikers could also hike north from Harts Pass, touch the monument at the northern terminus, turn around and hike south to Mexico.

Either way, don't worry about US border patrol ruining your hike.
Part of thru hiking is adapting to change.
There could be a 100 miles fire closure in your way.. you will find a way around it.
This issue with border patrol is minor compared to the sum total of your long hike.
Go ahead and apply for the entry papers with Canada. If you get rejected just turn around at the border and hike back to Harts pass. Just adds a day and change to your hike.
Frankly, I went to Manning and it was cool and all but i was jealous of my hiker buddies that returned to Harts pass.. they were still on trail!

The problem is not so much Canada's policy but the US policy. At least Canada allows most US citizens to cross the border into Canada on the PCT. Going the other way, even US citizens in good standing are subject to enormous fines and imprisonment if caught crossing the border southbound from Canada to the US except at established ports of entry–of which the PCT is not one.

The US doesn't allow foreigners in who have ever been arrested–even if never convicted–on drug charges, so why can't Canada exclude those convicted of a DUI? Since when is driving under the influence, cause of so many wasted lives, not a serious offense?

Nothing wrong with Canada or their policies at all.
Sovereign Nation with a very generous policy towards "American" PCT hikers.
Canada even has an actual process for entry to their country via the Pacific Crest trail.
The US has no policy at all.
Very civilised.
Ignore the fact that nobody will ever ask to see that permit.
Certainly not US customs on your way back to the US thru Vancouver.
It is almost as if it would be better to NOT have asked, knowing you would be rejected, and then enter and face the possibility of what.. being kicked out… to the US.
Nudge nudge.. wink wink…
The problem with that approach is that in the future Canada might decide on a more restrictive policy towards PCT hikers.
Every choice we make, no matter how it effects us, has consequences for those that follow in our wake.

This probably is checked if you want a visa (staying more than 180 days).

I think you can still gain entry into Canada with just a Government issued ID (e.g., driver's license), but check the CBSA website.

In 2006 I made a trip to Algonquin National Park crossing near Buffalo, NY. I got in with just my driver's license. I did not have my passport with me since this was a spur of the moment trip. I did have major problems getting back into the US without a passport, because without a passport they wanted two forms of government issued ID and I only had one. Of course my normally cheerful and patient attitude towards government bureaucracy did not help :)

In 2007 & 2008 I traveled several times to Canada via the airport in Vancover, Canada. Takes a little time to clear customs, mostly due to the lines of people. Again, more difficult and time consuming to leave and get back into the US. But this time I had my passport. If you do not have a passport, apply early as sometimes this can be a timely process.

My friend had this exact problem. He even tried to enter early this year on a ski tour, and because it was (literally) 2 days before the 10 YEAR mark, they turned him around. I would say she isn't getting in. Better to hike back to Harts Pass?